A previous type of socket is disclosed in U.S. Pat. No. 5,873,752 describing an electrical connection for a trailer pulled by a vehicle. That patent discloses a unitary socket and contact insert, wherein the contact insert contains flat terminals with elastically bent contact surfaces that are inserted in corresponding openings of the contact support insert. To seal the socket, after the flat terminals are inserted, the plug-in openings are sealed with a liquid sealant. However, during use the contact surfaces of the flat terminals or the flat terminals itself often bend away when a plug is inserted into the socket leading poor electrical contact.